Heavy duty flexible drill pipe



J. A. zUBLlN 2,717,146

HEAVY DUTY FLEXIBLE DRILL MPE 2 Sheets-Sheet l IN V EN TOR. Jon Zzlzzwurm ATTORNEYS Sept. 6, 1955 Filed April 9, 195s 02 Wan? M22 Sept. 6,1955 J. A. zUBLlN 2,717,146

HEAVY DUTY FLEXIBLE DRILL PIPE Filed April 9, 1953 2 Sheets-Sheet 2.47TORNEYS HEAVY DUTY FLEXIBLE DRILL PIPE John A. Zublin, Los Angeles,Calif.

Application April 9 1953, Serial No. 347,665

6 Claims. (Cl. Z55- 28) This invention relates to heavy duty flexibledrill pipe. Heavy duty flexible drill pipe is used quite extensively inthe drilling of curved drain holes deviating from a vertical well bore.It is the purpose and objective of the present invention to provide aheavy duty flexible drill pipe that is especially well adapted for suchuse.

The present invention constitutes an improvement on the general type ofheavy duty flexible drill pipe diS- closed in my prior U. S. Patent2,515,366, it being recognized that a variety of intermeshing teethconfigurations may be used within the scope of the instant inventionother than disclosed in such patent.

While the heavy duty flexible drill pipe of my prior patent has provedhighly meritorious, instances are sometimes encountered when theintermeshing teeth of the independent sections of the drill pipe throughwhich torsional force is applied become worn there is a tendency for thesections to buckle which permits a greater flexibility than contemplatedfor the particular drill pipe and furthermore increases the hazard ofbreaking the intermeshing teeth and possibly losing the portion of thedrill string and the bit below the point of severance.

In its more specific aspects the present invention contemplates theprovision of means for predetermining and limiting the extent of llexureof the heavy duty flexible drill pipe irrespective of wear on theintermeshing teeth of the individual sections.

Further and more specific advantages f this invention will becomeapparent as the description thereof proceeds which will be given inconnection with the vaccompanying drawings from a part thereof and, inwhich:

Figure l is a fragmentary view in side elevation with part shown insection illustrating one embodiment of my invention. v

Figure 2 is a cross-sectional view in the direction of the arrows takenon line 2-2 of Figure 1.

Figure 3 is a fragmentary cross-sectional view illustrating a modifiedform of my invention.

Figure 4 is a detailed cross-sectional view in the direction of thearrows taken along the line 4-4 of Figure 3 and Figure 5 is adiagrammatic fragmentary view illustrating the method of cutting away aportion of the intermeshing teeth on one of the sections of the heavyduty flexible drill pipe.

By reference to Figure l it will be observed that the heavy dutyflexible drill pipe of the present invention is made up of a series ofindependent interconnecting sections such as 10, 11 and 12. It will beunderstood that the uppermost of these independent sections is threadedat a free end to be received in the lower end of a conventional rotarydrill string as more fully illustrated in Figure l of my prior Patent2,515,366, and the lowermost section of the heavy duty flexible drillpipe will be provided with means for interconnection with like units ofheavy duty flexible drill pipe or with a drill'bit, asthe case may be.Returning now to a description of one of the duplicate sections 10, 11,and 12, it should be observed that in both the modification ,e ICC of myinvention illustrated in Figure 1 and that illustrated in Figure 3 theintermeshing teeth carrying elements of the sections are formed in thesame manner. Their manner of formation can perhaps best be described byinitial reference to Figure 3 wherein the annular welds 13 and 14 definethe upper and lower ends of what originally constituted a tubular steelbillet. This tubular steel billet is severedV by an appropriate cuttingtorch along a line defining the configuration of the intermeshing teeth.It is the character of the torch that determines the width of the slot`15 (Fig. l) between intermeshing teeth such as 16 and 17. After anumber of tubular billets have been thus severed by a cutting torch,their previously machined ends formed to provide the overlapping joint18 (Fig. 3) are welded together as indicated at 13 and 14. Thus, infinal assembled form, any given section of the heavy duty flexible drillpipe is made up of one end of one tubular steel billet and the oppositeend of another tubular steel billet.

In both modifications of my invention there' extends through the heavyduty flexible drill pipe an impervious conduit 19 which may be anarmored hose for the conveyance of the high pressure hydrauliccirculating drilling medium as more particularly exemplified in my priorPatent 2,585,207. Referring again to the modification of Figure 1, itwill be observed that each of the sections such as 10, 11, and 12, havesecured to the exterior Wall thereof a tubular member 20 which may beappro priately welded to its associated section such as 10, 11, and 12,through the medium of a Weld such as indicated at 21. Each of thetubular members 20 projects well beyond the Vteeth of its associatedsection. The inner Wall of the projecting portion of each of thetublllar members 20 is cut away to provide the outward taper indicatedat 22.

The arrangement is therefore such that when a given section such as 12is moved to the left, with reference to the section 11 as shown inFigure l, such movement will be limited by contact of that portion ofthe outer wall of section 12 that is telescopically received within thetubular member 20 when such portion of section 12 strikes the taperedsurface 22 of the tubular member 20 carried by section 11.

It will be appreciated that there is a much larger area of contactbetween the tapered surface 22 of any given tubular member 20 and theouter wall of the next adjacent section than there is between thesurface of the intermeshing teeth. Therefore, even though the contactingsurfaces of the intermeshing teeth may wear somewhat, the tubularmembers 20 will effectually limit the extent of llexure of the heavyduty flexible drill pipe. Additionally in the form of the inventionshown in Figure 1 the tubular members 20 act as shields that preventcontact of the teeth of the various sections of the heavy duty flexibledrill pipe with the wall of the well bore safeguarding .the same fromabrasive wear.

Now referring to the 'modification of Figure 3, this modificationdiffers primarily from the modication of Figure 17in that the tubularmembers'designated 23 in Figure 3 are carried on the interior wall ofthe associated sections designated 24 and 25 in Figure 3 rather than onthe exterior thereof. The upper ends of the tubular members 23 arerespectively held in the lower ends of sections such as 24 and 25 byso-called rivet welds. Radial .holes kindicated at 26 and 27 in Figure 4are drilled through sections -24 and 25 and the rivet welds whichinterlock sections 24 and 25 respectively to their associated tubularmembers 23, are positioned in these' openings with the respectivesections 24 and 25 and the associated tubular members 23 held in`predetermined telescopic relationship. In this modification the outerwall .at the lower end of each ofthe tubular members 23 is cut away toprovide the inwardly tapered surface 28 against which the inner wall ofthe next adjacent section of the heavy duty flexible drill pipe isadapted to engage and to thereby limit the extent of flexure of theheavy duty iiexible drill pipe. Additionally inthis modiication in orderto facilitate the requisite freedom of movement of the intermeshingteeth of adjacent sections a portion, that is the inner corners of theteeth at the end of each section telescopically received in the tubularmember 23, are cut away as indicated at 29 in Figure 3.

In this modication of Figure 3, as well as in the modication of Figurel, there is a positive limitation on the extent of angular movement ofthe sections of the heavy duty flexible drill pipe which limitation ofangular movement is not dependent solely upon the width of the torch cutbetween the intermeshing teeth.

In Figure 5 there is diagrammatically illustrated a method by which theportions of the intermeshing teeth of one of the sections may be cutaway to provide the cut out portions indicated at 29 in Figure 3.Pursuant to this method the sections 24 and 25, prior to the positioningof a tubular member 23 in the section 24, are moved progressively totheir maximum permitted extent of relative angular movement and thecutting torch 30 is advanced circumferentially along the inner wall ofsection 24. In this way the teeth of section 25 will have the requisitefreedom of movement to permit the required angular displacement afterthe tubular member 23 has been assembled in section 24.

From the foregoing description it will be apparent the present inventionprovides a heavy duty flexible drill pipe possessing positive means forcontrolling the degree of ilexure of the heavy duty tlexible drill pipeirrespective of wear on the intermeshing teeth of the sections thereofand which relieves the teeth from undue strain tending to cause the sameto crack or shear.

Having thus described my invention, what -I claim is:

l. A heavy duty flexible drill pipe comprising an elongated tubularmember subdivided into a plurality of sections of rigid pipe ofsubstantial Wall thickness in end to end relationship with a pluralityof teeth and complementary recesses on the opposite ends of theintermediate sections, the teeth of one section being positioned in therecesses and loosely interlocking the teeth of the adjacent sectionswith appreciable clearance to form a loose joint permitting limitedrelative angular movement in any direction between the sections, atubular member coaxially secured to each of said sections and projectingbeyond the teeth at one end thereof, the extended portion of saidtubular member overlapping and being spaced from an end portion of thenext adjacent section to be contacted by and limit the relative angularmovement of said next adjacent section.

2. A heavy duty exible drill pipe comprising an elongated tubular membersubdivided into a plurality of sections of rigid pipe of substantialwall thickness in end to end relationship with a plurality of teeth andcomplementary recesses on the opposite ends of the intermediatesections, the teeth of one section being positioned in the recesses andloosely interlocking the teeth of the adjacent sections with appreciableclearance to form a loose joint permitting limited relative angularmovement in any direction between the sections, a tubular membercoaxially secured to the exterior wall of each of said sections andprojecting beyond the teeth at one end thereof, the extended portion ofsaid tubular member overlapping and being spaced from an end portion ofthe next adjacent section to be contacted by and limit the relativeangular movement of said next adjacent section,

3. A heavy duty flexible drill pipe comprising an elongated tubularmember subdivided into a plurality of sections of rigid pipe ofsubstantial wall thickness in end to end relationship with a pluralityof teeth and complementaryrecesses on the opposite ends of theintermediate sections, the teeth of one section being positioned in therecesses and loosely interlocking the teeth of the adjacent sectionswith appreciable clearance to form a loose joint permitting limitedrelative angular movement in any direction between the sections, atubular member coaxially secured to the interior wall of each of saidsections and projecting beyond the teeth at one end thereof, theextended portion of said tubular member overlapping and being spacedfrom an lend portion of the next adjacent section to be contacted by andlimit the relative angular movement of said next `adjacent section.

4. A heavy duty flexible drill pipe comprising an elongated tubularmember subdivided into a plurality of sections of rigid pipe ofsubstantial wall thickness in end to end relationship with a pluralityof teeth and complementary recesses on the opposite ends of theintermediate sections, the teeth of one section being positioned in therecessesand loosely interlocking the teeth of the adjacent sections withappreciable clearance to form a loose joint permitting `limited relativeangular movement in any direction between the sections, a tubular membercoaxially secured to the exterior wall of each of said sections andprojecting beyond the teeth at one end thereof, the inner wall of theextended portion of said tubular member being tapered outwardly towardits free end with said tapered surface overlapping and being spaced froman end portion of the next adjacent section to be contacted by and limitthe relative angular movement of said next adjacent section.

5. A heavy duty flexible drill pipe comprising an elongated tubularmem-ber subdivided into a plurality of sections of rigid pipe ofsubstantial wall thickness in endI to end relationship with a pluralityof teeth and complementary recesses on the opposite ends of theintermediate sections, the teeth of one section being positioned in therecesses and loosely interlocking the teeth of the adjacent sectionswith appreciable clearance to form a loose joint permitting limitedrelative angular movement in any direction between the sections, atubular member coaxially secured to the interior wall of each of saidsections and projecting beyond the teeth at one end thereof, the outerwall of a substantial portion of the extended portion of said tubularmember being tapered inwardly to provide a tapered surface overlappingand being spaced from an end portion of the next adjacent section to becontacted by and limit the relative angular movement of said nextadjacent section.

6. A heavy duty exible drill pipe comprising an elongated tubular membersubdivided into a plurality of sections of rigid pipe of substantialwall thickness in end to end relationship with a plurality of teeth andcomplementary recesses on the opposite ends of the intermediatesections, the teeth of one section being positioned in the recesses andloosely interlocking the teeth of the adjacent sections with appreciableclearance to form a loose joint permitting limited relative angularmovement in any direction between the sections, a tubular membercoaxially secured to the interior wall of each of said sections andprojecting beyond the teeth at one end thereof, the teeth fz, of saidsections at the ends thereof opposite said projecting tubular memberhaving their inner surfaces tapered Y to facilitate angular movement ofsaid sections, the outer wall of a substantial portion of the extendedportion of said tubular member being tapered inwardly to provide atapered surface overlapping and being spaced from an end portion of thenext adjacent section to be contacted by and limit the relative angularmovement of said next adjacent section.

References Cited in the file of this patent UNITED STATES PATENTS1,500,921 Bramson et al. July 8, 1924 2,432,278 Bratz Dec. 9, 19472,515,366 Zub-1in July 18, 1950 2,645,456 rilhompson July 14, 19.53

